Added interfaces to the Mirror Clients and updates the tests to use t…

[TiagoFroisPereira]

Created a interface for each Mirror Client and the extension for the IServiceCollection that allows to register this dependencies and use this interfaces as DI that simplify the usage.

How to use:

• In the startup/program file add: services.AddHasgraph() -> receives the HederaNetwork enum containing the values (Mainnet, TestNet, PreviewNet)

• Inject the interfaces IMirrorRestClient or IMirrorGrpcClient depending on your needs